The homopolymer of 7,oxa-bicyclo(2;2;1)heptane and of its alkyl-derivatives is known and described in the technical literature. This homopolymer, although shows a crystallinity at X-rays, and is poorly soluble in most common solvents, suffers from the drawback that it has a melting temperature (generally higher than 350.degree. C.) higher than its decomposition temperature. This set of properties make the homopolymer not much interesting from a industrial viewpoint, due to the fabricating difficulties.